DISCOVERY  AND  INVENTION 


> 


BY 

ALEXANDER  GRAHAM  BELL  ' : 


Reprinted  from  the  National  Geographic  Magazine,  June,  1914 

Copyright,  1914,  by  the  National  Geographic  Society 


WASHINGTON,  D.  C. 

PRESS  OF  JUDD  & DETWEILER,  INC. 
1914 


Digitized  by  the  Internet  Archive 
in  2017  with  funding  from 

University  of  Illinois  Urbana-Champaign  Alternates 


https://archive.org/details/discoveryinventiOObell 


mr  19  n 


DISCOVERY  AND  INVENTION* 

By  Alexander  Graham  Bell 


I AM  going  to  begin  tonight  by  asking 
you  a rather  startling  question : Did 
you  ever  put  your  head  under  water 
and  chuck  two  stones  together  to  see  what 
the  sound  is  like?  If  you  have  never 
done  that,  try  it,  and  you’ll  get  a new 
sensation.  I did  it  once,  and  it  sounded 
as  if  a man  were  hammering  for  all  he 
was  worth  at  my  very  ear. 

I then  took  two  tiny  little  pebbles  and 
tapped  them  together  quite  lightly  under 
water,  and  it  sounded  like  a man  knock- 
ing at  the  door.  It  was  rather  startling 
to  hear  such  a loud  noise  from  such  a 
slight  cause. 

Of  course,  the  question  at  once  arose 
in  the  mind : How  far  off  could  we  hear 
the  sound?  So  I sent  a boy  a hundred 
feet  up  the  beach  with  a couple  of  stones, 
directing  him  to  strike  them  together 
under  water.  I then  submerged  my  head, 
and  I could  hear  the  sound  about  as  read- 
ily as  before. 

Well,  I determined  to  test  the  maxi- 
mum possible  distance,  and  sent  the  boy 
across  the  bay  in  a boat  to  the  other  side, 
to  a point  at  least  a mile  away  from  the 
place  where  I stood,  and  I followed  him 
with  field  glasses  to  see  that  he  carried 
out  my  instructions.  I saw  him  land  on 
the  other  side,  take  off  his  coat,  roll  up 
his  sleeves,  and  go  down  to  a little  plank 
wharf  on  the  shore  rising  only  a few 
inches  out  of  water.  He  lay  down  upon 
the  wharf,  face  downward,  and  put  his 
hands  into  the  water,  and  I then  knew  he 
was  making  signals  with  these  stones. 

Now,  the  question  was : Could  I hear 
him  ? Quietly  and  gently  I went  into  the 
water  at  my  side  of  the  bay,  submerged 
my  head,  and  listened  for  all  I was  worth. 
Well,  you  know,  the  signals  came  per- 
fectly clear  and  distinct,  through  more 
than  a mile  of  water,  to  my  ear.  It  was 
one  of  the  most  astonishing  revelations  of 
what  could  be  done  with  water. 

You  know  if  you  look  away  in  the 
distance  at  a man  firing  a gun  you  can 
see  the  flash,  and  after  a time  you  get  the 


report ; the  sound  takes  time  to  travel 
through  the  air.  It  goes  about  1,100  feet 
per  second ; but  in  the  water  it  goes  five 
times  as  fast  as  that — over  5,000  feet  per 
second.  Water  is  a much  better  conductor 
of  sound  than  air. 

DO  FISH  SIGNAL  TO  ONE  ANOTHER  BY 
SOUNDS  ? 

Reflecting  upon  these  various  experi- 
ments, the  thought  occurred:  If  two  little 
stones  tapped  together  can  be  heard  under 
water,  why,  every  tiny  lobster  that  snaps 
his  claws  must  make  an  audible  click.  I 
wonder  if  there  are  creatures  in  the  water 
that  signal  to  one  another  by  sound. 

Well,  I had  occasion  to  try  it  once. 
Bathing  in  the  Grand  River  in  Ontario  a 
great  many  years  ago,  I put  my  head  very 
gently  under  water  and  listened,  and,  sure 
enough,  “tick,  tick,”  came  a sound  like  a 
grasshopper’s  chirrup,  and  a little  while 
after  that  a chirrup  on  the  other  side. 
There  were  creatures  under  the  water 
that  were  calling  to  one  another. 

I don’t  know  whether  all  fish  make 
sounds  or  not,  but  there  are  some  fish  that 
certainly  do.  The  drumfish  on  our  coast 
drums  away  in  the  water  so  loudly  that 
you  can  hear  him  while  you  are  walking 
on  the  shore. 

It  is  also  a significant  fact  that  all  fish 
have  ears.  Why  should  they  have  ears 
if  there  is  nothing  for  them  to  hear? 

Of  this  we  may  be  certain — that  there 
is  a whole  world  of  sound  beneath  the 
waves  waiting  to  be  explored , perhaps  by 
some  of  you. 

I have  wanted  you  to  see  how  one  obser- 
vation leads  to  another.  Starting  with  a 
very  small  thing — the  chucking  together 
of  two  pebbles  under  water,  and  follow- 
ing this  up  by  other  observations — we 
broaden  our  field  of  knowledge  and  reach 
generalizations  of  considerable  magni- 
tude as  the  resultant  of  numerous  small 
thoughts  brought  together  in  the  mind 
and  carefully  considered. 


*An  address  to  the  graduating  class  of  the  Friends’  School,  Washington,  D.  C.,  delivered 
May  22,  1914. 


THE  NATIONAL  GEOGRAPHIC  MAGAZINE 


650 


OUT  OE  THE  BEATEN  TRACK 

I was  walking  along  the  road  one  day 
in  my  country  place  in  Nova  Scotia, 
when  the  idea  occurred  to  leave  the 
beaten  track  and  dive  into  the  woods. 
Well,  I had  not  gone  50  feet  before  I 
came  upon  a gully,  and  down  at  the  bot- 
tom was  a beautiful  little  stream.  I never 
knew  of  it  before. 

Of  course,  I was  not  satisfied  with  the 
mere  discovery,  but  went  down  into  the 
gully  and  explored  it  right  and  left.  I 
followed  it  up  to  its  source.  I followed 
it  downward  for  half  a mile,  through  a 
beautiful  moss-grown  valley,  until  at  last 
the  little  streamlet  discharged  into  a pond, 
and  away  in  the  distance  I could  see  a 
sea  beach  with  the  open  water  beyond. 

Now,  just  think  of  that!  Here  was  a 
beautiful  gorge,  half  a mile  long,  right  on 
my  own  place,  and  coming  at  one  point 
within  50  feet  of  a well-trodden  road,  and 
I never  knew  of  its  existence  before.  We 
are  all  too  much  inclined,  I think,  to  walk 
through  life  with  our  eyes  shut.  There 
are  things  all  round  us  and  right  at  our 
very  feet  that  we  have  never  seen,  be- 
cause we  have  never  really  looked. 

Don't  keep  forever  on  the  public  road, 
going  only  where  others  have  gone  and 
following  one  after  the  other  like  a flock 
of  sheep.  Leave  the  beaten  track  occa- 
sionally and  dive  into  the  woods.  Every 
time  you  do  so  you  will  be  certain  to  find 
something  that  you  have  never  seen  be- 
fore. Of  course  it  will  be  a little  thing, 
but  do  not  ignore  it.  Follow  it  up,  ex- 
plore all  round  it ; one  discovery  will  lead 
to  another,  and  before  you  know  it  you 
will  have  something  worth  thinking  about 
to  occupy  your  mind.  All  really  big  dis- 
coveries are  the  results  of  thought. 

the  beginnings  oe  invention 

I dare  say  you  have  all  heard  of  that 
celebrated  painter  who  would  never  allow 
any  one  to  mix  his  colors  for  him.  He 
always  insisted  on  doing  that  himself,  and 
at  last  one  of  his  students,  whose  curi- 
osity had  been  aroused,  said : “Professor, 
what  do  you  mix  your  colors  with?” 
“With  brains,  sir,”  said  the  professor. 
Now,  that  is  what  we  have  to  do  with 
our  observations. 


I think  I left  you  with  your  head  under 
water  listening  to  the  clicking  of  two 
stones.  Now,  let  us  see  whether  we  can- 
not use  our  brains  to  get  you  out  of  so 
awkward  a predicament.  We  will  then 
have  entered  the  realm  of  invention,  as 
distinct  from  discovery. 

Why  should  we  not  simply  put  the  ear 
to  the  water  instead  of  submerging  the 
whole  head? 

Why  should  we  not  ring  a bell  under 
water  instead  of  clicking  stones  together 
to  make  a noise.  An  ordinary  dinner 
bell  would  do.  Empty  it  of  air  and  ring 
it  under  water,  and  the  sound  can  be 
heard  by  a submerged  ear  at  a great  dis- 
tance away. 

It  is  a little  awkward,  however,  to  keep 
the  ear  continuously  submerged  on  ac- 
count of  the  movements  of  the  surface 
water.  Every  now  and  then  a little  wave 
will  slap  you  in  the  face,  and  you  are  apt 
to  choke  if  you  are  caught  unprepared. 

Why  would  it  not  be  better  to  transmit 
the  sound  vibrations  from  the  water  to 
the  ear  through  some  intervening  mech- 
anism, and  thus  obviate  the  necessity  of 
submerging  the  ear  at  all  ? 

I have  tried  submerged  hearing  tubes 
of  various  kinds  and  planks  of  wood  par- 
tially submerged,  with  the  ear  applied  to 
the  part  out  of  water. 

If  you  put  your  ear  to  the  bottom  of  a 
boat — inside,  of  course,  not  outside — you 
can  hear  a bell  at  a distance  quite  readily. 
It  still  is  a little  awkward,  however,  to 
get  your  ear  against  the  planks  of  the 
boat;  but  brains  will  help  you  out.  Just 
fix  a telephone  transmitter  to  the  planks 
of  the  boat,  and  you  can  sit  at  ease  with 
the  telephone  receiver  at  your  ear. 

You  may  even  put  the  telephone  trans- 
mitter overboard.  It  then  becomes  a sub- 
merged ear  and  will  listen  for  you  under 
water. 

EISHING  WITH  TELEPHONES  , 

I have  often  thought  I should  like  to 
go  on  the  banks  of  Newfoundland  and 
fish  with  a telephone.  If  you  were  to 
send  the  transmitter  down  among  the 
codfish  with  the  bait,  perhaps  you  would 
find  something  there  to  hear.  I have 
never  tried  it.  I will  leave  that  to  you. 

We  now  have  numbers  pf  steamers 


DISCOVERY  AND  INVENTION 


651 


upon  the  Atlantic  fitted  with  telephone 
transmitters  attached  to  the  thin  iron  skin 
of  the  hull,  away  down  in  the  hold,  and 
the  receiving  telephone  on  the  bridge. 

On  shore  there  are  huge  bells  at  light- 
house stations  making  fog-signals  under 
water,  and  each  steamer  as  it  approaches 
the  coast  can  pick  up  these  submarine 
sounds  at  a distance  of  io  miles. 

Here  is  a completed  invention  which 
some  patient  observer  has  evolved  from 
just  such  little  beginnings  as  those  I have 
described. 

I doubt  whether  you  could  hear  a fog- 
signal  through  the  air  at  any  such  dis- 
tance as  that.  The  air  is  at  best  but  a 
poor  conductor  of  sound,  and  many  illu- 
sions of  hearing  are  possible. 

It  is  difficult  in  any  case  to  tell  the 
exact  direction  of  a sound  in  a fog.  It  is 
possible,  too,  that  you  might  have  an 
echo  from  the  sails  of  a vessel,  and  you 
would  then  be  entirely  misled  as  to  the 
direction  of  the  signal  station. 

Then,  again,  an  island  anywhere  near 
casts  a sound-shadow  upon  the  water. 
The  sound-wave  striking  the  island  is  de- 
flected up  into  the  sky,  and  you  would 
have  to  go  up  in  a balloon  to  hear  it,  and 
it  may  not  come  down  again  to  the  sur- 
face for  a mile  or  two  beyond  the  island. 
A ship  quite  close  to  the  island  might  not 
hear  the  sound.  The  captain,  knowing  that 
the  fog-horn  should  be  heard  at  least  a 
mile  or  two  away,  imagines  himself  to  be 
much  farther  off  than  he  really  is,  and  in 
the  midst  of  the  fog  he  may  become  con- 
scious of  the  presence  of  the  land  only  by 
actual  contact  with  it. 

Then  the  transmitting  qualities  of  the 
air  are  subject  to  variations  on  account 
of  unusual  atmospheric  conditions.  You 
« may  be  quite  near  a fog-signal  station 
and  yet  hear  the  sound  so  faintly  that  you 
imagine  it  to  be  far  away.  You  may  even 
get  an  echo  from  the  clouds;  but  then 
you  know  you  are  subject  to  an  illusion, 
for  the  sound  seems  to  come  from  the  sky. 

Now,  sounds  can  be  transmitted 
through  the  water  to  far  greater  dis- 
tances than  through  the  air,  and  atmos- 
pheric conditions  have  no  effect. 

I don’t  want  to  confine  your  attention 
to  inventions  that  already  have  been 
made.  I want  to  show  you  also  that 


there  is  room  for  something  new.  We 
don’t  know  everything  yet  and  the  list  of 
possible  inventions  is  not  yet  closed. 
Take,  for  example,  the  case  we  have  been 
talking  about,  the  transmission  of  sound 
through  water. 

EXPLORING  UNDER  THE  SEA 

Three-quarters  of  the  earth’s  surface- 
is  under  water  and  has  not  yet  been  ex- 
plored,^at  least  to  any  great  degree.  The 
only  way  we  have  of  reaching  the  moun- 
tains and  valleys  at  the  bottom  of  the  sea 
is  by  sending  down  a sounding  line  and 
bringing  up  a specimen  of  the  bottom  at- 
tached to  the  sinker.  It  is  no  joke,  how- 
ever, to  reach  the  bottom  of  the  deep, 
blue  sea  through  one  mile  or  even  two 
miles  of  water,  and  it  takes  several  hours 
to  make  a single  sounding.  Just  think  of 
all  the  time  and  labor  involved  in  merely 
ascertaining  the  depth. 

Why  should  we  not  send  down  a sound 
instead  and  listen  for  an  echo  from  the 
bottom.  Knowing  the  velocity  of  sound 
in  water  and  the  time  taken  for  the  echo 
to  reach  the  ear,  we  should  be  able  to 
ascertain  the  depth  of  the  deepest  part 
of  the  ocean  in  less  than  four  seconds  in- 
stead of  more  than  four  hours.  Here  is 
something  worth  doing.  It  has  never 
been  tried.  I have  suggested  it  a number 
of  times,  and  I will  now  pass  on  the 
thought  to  you  in  the  hope  that  some  of 
you  may  care  to  take  it  up. 

Suppose  you  are  on  one  of  those  steam- 
ers provided  with  transmitter  hulls  and 
telephone  ear-pieces,  and  you  send  down 
a little  piece  of  gun-cotton  or  other  ex- 
plosive material  to  a safe  distance  below 
your  ship  and  then  explode  it  by  an  elec- 
trical contact.  The  sound-wave  from  the 
explosion  will,  of  course,  go  down  to  the 
bottom  and  then  be  reflected  up  again,  so 
that  after  a certain  length  of  time  you 
should  get  an  echo  from  the  bottom. 

Not  only  should  you  be  able  to  tell  the 
depth  of  the  ocean  by  an  echo  from  the 
bottom,  but  you  might  perhaps  learn 
something  of  the  nature  of  the  bottom 
itself.  A flat  bottom  should  yield  a single 
sharp  return,  whereas  an  undulating  bot- 
tom should  yield  a multiple  echo,  like 
that  heard  when  you  fire  a pistol  among 
hills. 


652 


THE  NATIONAL  GEOGRAPHIC  MAGAZINE 


Then,  as  you  approach  the  shore  you 
should  get  resonance  effects,  like  those 
perceived  when  you  shout  out  loudly  in 
an  empty  cave. 

However,  I must  not  take  up  your  time 
in  speaking  upon  only  one  subject.  What 
I want  to  direct  your  attention  to  is  that 
both  discovery  and  invention  are  not 
things  that  come  all  at  once.  They  arise 
from  very  simple  beginnings.  A small 
observation,  patiently  followed  up  by 
other  observations  equally  small,  leads 
gradually  to  a big  conclusion.  Do  not 
ignore  little  things;  life  itself  is  made  up 
of  them,  and  there  is  a good  old  Scotch 
saying  that  bears  upon  the  point : 

“Mony  a mickle  maks  a muckle.” 

A great  many  small  things  make  a big 
one.  Any  one,  if  he  will  only  observe, 
can  find  some  little  thing  he  does  not 
understand  as  a starter  for  an  investiga- 
tion. 

AN  EXPERIMENT  AT  HOME 

T had  rather  a curious  illustration  of 
this  the  other  day  in  my  own  house.  I 
told  a lad  who  was  waiting  upon  me  that 
I wanted  to  make  some  experiments  with 
a bottle  of  water,  and  told  him  to  bring  a 
bottle  of  very  hot  water  from  the  kitchen, 
and  be  sure  that  it  was  quite  full.  He 
soon  returned  with  a big-bodied  bottle 
provided  with  a long  and  narrow  neck, 
filled  to  the  brim,  and  put  it  on  the  man- 
telpiece and  went  downstairs.  After  the 
water  had  cooled,  I rang  the  bell  for 
John. 

“John,”  I said,  “I  thought  I told  you 
to  fill  that  bottle  quite  full.” 

“So  I did,  sir,”  he  replied. 

“Well,  look  at  it  now  ; it’s  not  nearly 
full;  the  neck  is  quite  empty.” 

John  assured  me  that  he  had  not 
touched  the  bottle  since  he  first  put  it  up, 
and  I assured  him  that  I had  not  poured 
any  of  the  water  out. 

“Well,”  I said,  “what  has  become  of 
the  water?” 

He  was  quite  nonplussed  at  first,  and 
then  he  began  to — to — ratiocinate,  .and 
said : “The  water  was  quite  hot  when  I 
put  it  in;  there  was  steam  coming  from 
it.  The  water  must  have  evaporated.” 

I made  no  comment,  but  looked  at  him 
and  said : “Let’s  try  it  again.  You  fill 


that  bottle  chock  full  of  hot  water  this 
time,  and  then  cork  it  so  that  no  steam 
can  escape.” 

He  did  so ; and  by  and  by  I rang  the 
bell  again,  and  up  came  John. 

“John,”  I said,  “I  thought  you  filled 
that  bottle  quite  full.” 

“So  I did,  sir,”  he  replied. 

“Well,  look  at  it  now;  it’s  not  nearly 
full.”  John  assured  me  that  he  had  not 
touched  the  cork,  and  I replied:  “Well, 
what  has  become  of  the  water?”  John 
said  he  didn’t  know.  He  admitted  that 
some  of  it  had  evidently  gone,  but  where 
it  had  gone  he  couldn’t  for  the  life  of  him 
conceive,  and  he  hasn’t  found  out  yet. 

I am  sorry  now  I didn’t  think  of  telling 
John  to  weigh  the  bottle  when  he  first 
brought  it  up,  for  by  weighing  it  again 
he  could  have  found  out  exactly  how 
much  had  disappeared. 

If  John  hadn’t  given  up  he  might  have 
arrived  by  degrees  at  a realization  of  the 
principle  upon  which  a thermometer 
works. 

A thermometer  is  an  instrument  for 
measuring  heat,  and  whenever  you  can 
measure  a phenomenon  you  have  a basis 
upon  which  may  be  built  a science ; in 
fact,  all  science  is  dependent  upon  meas- 
urement. 

When  you  measure  heat  you  get  the 
science  of  thermo-dynamics,  and  thermo- 
this  and  thermo-that.  When  you  meas- 
ure the  pressure  of  the  atmosphere  by  a 
barometer  you  lay  the  basis  for  the 
science  of  meteorology  and  a whole  lot 
of  sciences  dependent  upon  atmospheric 
measurements.  So  you  have  sciences 
based  upon  the  measurement  of  sound 
and  light;  but  you  have  no  science  of 
odor. 

MEASURING  AN  ODOR 

Did  you  ever  try  to  measure  a smell? 
Can  you  tell  whether  one  smell  is  just 
twice  as  strong  as  another.  Can  you 
measure  the  difference  between  one  kind 
of  smell  and  another.  It  is  very  obvious 
that  we  have  very  many  different  kinds 
of  smells,  all  the  way  from  the  odor  of 
violets  and  roses  up  to  asafetida.  But 
until  you  can  measure  their  likenesses 
and  differences  you  can  have  no  science 
of  odor.  If  you  are  ambitious  to  found 
a new  science,  measure  a smell. 


DISCOVERY  AND  INVENTION 


653 


What  is  an  odor?  Is  it  an  emanation 
of  material  particles  into  the  air,  or  is  it 
a form  of  vibration  like  sound?  If  you 
can  decide  that,  it  might  be  the  starting 
point  for  a new  investigation.  If  it  is  an 
emanation,  you  might  be  able  to  weigh  it ; 
and  if  it  is  a vibration,  you  should  be  able 
to  reflect  it  from  a mirror.  You  can  re- 
flect sound  and  light  and  heat,  and  I have 
even  warmed  my  hands  at  the  reflection 
of  a fire  in  a mirror.  Not  a glass  mirror, 
for  glass  is  opaque  to  radiant  heat.  A 
sheet  of  transparent  glass  makes  a fine 
fire-screen.  You  can  see  the  fire  through 
it,  but  it  cuts  off  the  heat.  When  you  try 
to  reflect  it  from  an  ordinary  looking- 
glass,  the  heat  has  to  go  through  the  glass 
in  order  to  reach  the  reflecting  surface 
behind  and  then  pass  through  the  glass  a 
second  time  in  order  to  get  out.  Take  a 
sheet  of  polished  metal — tin-foil  will 
do — or  any  metal  with  a bright  and  shiny 
surface  and  you  can  reflect  heat  from  it 
with  ease. 

Can  you  reflect  a smell  or  measure  its 
velocity  of  transmission?  If  you  can  do 
those  things  you  will  be  well  advanced 
on  the  road  to  the  discovery  of  a new 
science. 

the:  SMEXT  of  TFixurium 

Well,  that  reminds  me  of  a discovery 
that  started  with  a smell.  We  have  a 
very  rare  elementary  substance  known  as 
tellurium,  and  when  you  melt  it  with  a 
blow-pipe  it  gives  off  a smell.  We  can’t 
measure  it,  nor  even  describe  it ; but  if 
you  have  ever  smelled  it  you  will  know 
it  ever  after.  There  is  nothing  in  heaven 
or  on  earth  that  smells  like  that. 

Now,  you  know  it  is  the  object  of 
many  chemists  and  scientific  men  to  turn 
their  discoveries  to  some  practical  use. 
They  try,  through  chemical  and  other 
means,  to  convert  waste  products,  for  ex- 
ample, into  useful  things.  Indeed,  the 
utilization  of  waste  products  is  a charac- 
teristic of  the  age  in  which  we  live. 

Just  think  what  they  have  done.  Here 
is  a gas  manufactory  consuming  coal. 
After  the  gas  has  been  produced  we  have 
left  upon  our  hands  ashes  and  clinkers 
and  a lot  of  evil-smelling  tar.  Well,  the 
chemists  go  to  work  and  out  of  that  tar 
they  make  the  most  delightful  perfumes 


for  scenting  handkerchiefs,  and  nice 
sweet  essences  for  flavoring  puddings, 
and  the  most  beautifully  colored  dyes,  all 
made  from  coal-tar. 

Now,  there  was  a distinguished  chem- 
ist who  thought  he  saw  a chance  of  mak- 
ing something  valuable  out  of  the  waste 
products  obtained  in  the  manufacture  of 
sulphuric  acid.  Some  of  the  powder  he 
obtained  he  heated  with  a blow-pipe,  and 
at  once  perceived  the  characteristic  smell 
of  tellurium.  Here,  he  thought,  was  a 
rare  and  valuable  element  contained  in  a 
common  and  cheap  by-product  and  it 
might  pay  to  extract  it.  He  then  applied 
various  chemical  tests,  but  could  get  no 
other  indication  of  the  presence  of  tel- 
lurium excepting  the  smell.  All  the  re- 
actions declared  there  was  no  tellurium 
there. 

He  did  not  stop  with  this  observation, 
but  followed  it  up  and  began  reasoning 
about  it.  If,  he  thought,  there  is  no  tel- 
lurium here,  there  is  certainly  something 
that  has  a smell  very  like  it,  and  I know 
of  no  other  substance  on  earth  that  has  a 
smell  like  that.  Perhaps  there  may  be  a 
new  substance  here,  not  yet  discovered, 
which  resembles  tellurium,  at  least  in  the 
smell. 

He  knew  that  he  was  working  with  a 
regular  conglomerate  or  mixture  of  all 
sorts  of  materials,  many  of  which  he 
could  identify.  He  then  extracted  from 
the  mass  all  the  materials  he  knew  were 
there  to  see  if  there  was  anything  left ; 
and,  sure  enough,  a residue  appeared 
which  turned  out  to  be,  as  he  had  sus- 
pected, a new  elementary  substance  not 
heretofore  known  to  man. 

sexfnium  found 

He  termed  this  substance  selenium  be- 
cause it  resembled  tellurium.  The  word 
selenium,  you  know,  is  derived  from  a 
Greek  word  meaning  the  moon,  and  tel- 
lurium comes  from  the  Latin — tellus,  the 
earth.  The  two  substances  were  not  iden- 
tical, but  were  related  to  one  another  as 
the  moon  is  to  the  earth. 

Selenium  was  found  to  resemble  black 
sealing-wax  in  appearance.  It  had  a 
beautiful,  black,  glossy  surface,  and  in 
thin  films  was  transparent,  showing  ruby 
red  by  transmitted  light.  In  this,  its  vit- 


654 


THE  NATIONAL  GEOGRAPHIC  MAGAZINE 


reous  form,  it  was  a non-conductor  of 
electricity,  thus  differing  in  a remarkable 
degree  from  tellurium,  which  was  a good 
conductor. 

When,  however,  selenium  was  heated 
almost  to  the  fusing  point  and  then  al- 
lowed to  cool  very  slowly,  it  completely 
changed  its  appearance.  It  acquired  a 
dull  metallic  look,  like  lead ; and  in  this, 
its  crystalline  condition,  was  also  found 
to  be  a conductor  of  electricity,  but  of 
extremely  high  resistance.  A little  pencil 
of  crystalline  selenium  not  much  more 
than  an  inch  in  length  offered  as  much 
resistance  to  the  passage  of  an  electrical 
current  as  96  millions  of  miles  of  wire, 
enough  to  reach  from  here  to  the  sun, 
and  yet  it  was  a conductor.  That  was  a 
discovery.  Now.  comes  an  invention. 

Willoughby  Smith,  in  laying  the  At- 
lantic cable,  found  it  advisable  to  balance 
the  electrical  resistance  of  the  cable  dur- 
ing the  process  of  submersion  by  tre- 
mendous coils  of  well-insulated  wire. 
Why,  thought  he,  should  not  a little  bit 
of  selenium  balance  the  whole  cable  and 
enable  us  to  get  rid  of  all  this  complica- 
tion of  wire. 

He  succeeded  in  doing  this,  but  found 
the  electrical  resistance  very  variable.  At 
times  the  selenium  would  balance  the 
whole  cable  and  at  other  times  not  one- 
half  of  it. 

He  did  not  stop  with  this  observation, 
but  sought  the  cause  of  the  variation. 
He  multiplied  observations,  and  his  as- 
sistant, Mr.  May,  soon  discovered  that 
the  resistance  of  the  selenium  was  greater 
at  night  than  in  the  day. 

This  at  once  suggested  to  Willoughby 
Smith  the  thought  that  perhaps  the  elec- 
trical resistance  of  selenium  was  affected 
by  light,  and  he  proceeded  to  put  his  idea 
to  the  test  of  experiment.  He  shut  up 
the  selenium  in  a dark  box  near  a bright 
light,  and  found  that  when  the  lid  was 
open  the  resistance  went  down  and  when 
it  was  closed  it  rose  again.  Even  a 
shadow  falling  upon  the  selenium  affected 
its  electrical  resistance. 

SPEECH  FROM  A SUNBEAM 

Then  other  scientific  men  took  the  mat- 
ter up.  Professor  Adams,  of  King’s  Col- 
lege, England,  discovered  that  the  resist- 


ance varied  directly  with  the  intensity  of 
the  light  that  fell  upon  the  selenium. 
Then  I came  along  with  some  specula- 
tions concerning  the  possibilities  of  tele- 
phoning without  wires  by  varying  the  in- 
tensity of  a beam  of  light  by  the  action 
of  the  voice,  and  allowing  the  light  to 
fall  upon  a piece  of  crystalline  selenium. 
In  this  way  I thought  it  would  be  possi- 
ble to  get  speech  from  a sunbeam. 

Well,  I need  not  go  into  the  details, 
but  it  was  true.  I produced  the  photo- 
phone, an  instrument  for  talking  along  a 
beam  of  light  instead  of  a telegraph  wire. 
It  is  interesting  to  remember  that  all 
these  things  resulted  from  the  observa- 
tion of  a smell. 

When  I was  invited  to  talk  to  you  to- 
night I had  no  idea  of  what  to  say.  I 
thought  of  all  the  good  maxims  for  your 
future  conduct  in  life ; but  giving  advice 
to  young  people  is  out  of  my  line,  and  it 
seemed  to  be  better  to  choose  some  sub- 
ject with  which  I was  a little  familiar 
myself. 

How  discoveries  and  inventions  arise 
from  the  observation  of  little  things  is 
surely  a topic  worthy  of  your  considera- 
tion. I also  thought  it  would  be  interest- 
ing for  you  to  know  how  many  appar- 
ently impossible  results  have  been  actually 
achieved  by  the  patient  multiplication  of 
little  observations. 

It  was  only  a short  time  ago  that  if 
you  wished  to  express  the  idea  that  any- 
thing was  utterly  impossible  you  would 
say,  “I  could  no  more  do  that  than  I 
could  fly.”  I don’t  think  there  is  any  one 
here  who  is  too  young  to  have  heard  that 
expression.  It  was  the  height  of  impos- 
sibility that  we  should  fly,  and  here  men 
are  flying  in  the  air  today. 

It  is  only  a few  years  since  the  first 
man  flew,  and  we  are  only  at  the  begin- 
ning of  aviation.  What  a delightful  idea 
it  is  to  go  sailing  through  the  air.  The 
only  trouble  is  that  you  must  come  down, 
and  we  have  altogether  too  many  fatali- 
ties connected  with  the  work.  Here, 
then,  is  a subject  for  you  to  explore: 
How  to  improve  the  safety  of  the  flying 
machine.  How  to  produce  flying  ma- 
chines that  any  one  can  fly. 

We  know  perfectly  well  that  the  time 
is  coming,  and  is  almost  here,  when  it  will 


DISCOVERY  AND  INVENTION 


655 


be  an  every-day  thing  to  go  from  place  to 
place  through  the  air.  Perhaps  some  of 
you  may  find  a field  of  occupation  in 
bringing  this  about. 

BUYING  ACROSS  THE  ATLANTIC 

Even  today  we  have  startling  proposi- 
tions to  do  things  that  are  apparently  im- 
possible. A man  proposes  to  try  this 
summer  to  fly  across  the  Atlantic  Ocean 
in  a heavier-than-air  flying  machine.  The 
strange  thing  about  the  matter  is  that  ex- 
perts who  have  examined  into  the  possi- 
bilities find  that  he  really  has  a fighting 
chance. 

You  see  the  distance  is  less  than  2,000 
miles  from  Newfoundland  to  Ireland. 
This  means  that  if  you  could  go  at  100 
miles  an  hour  you  would  cross  the  At- 
lantic in  20  hours — less  than  a day.  Just 
think  of  that.  Well,  we  have  flying  ma- 
chines that  go  at  a greater  speed  than 
that.  We  already  have  machines  that 
coffid  cross  the  ocean  if  their  engines  can 
keep  going  for  20  hours. 

Of  course,  these  are  exceptional  ma- 
chines ; but  even  the  ordinary  machines 
of  today  make  50  miles  an  hour  with 
ease.  Now,  a flying  machine  flies  faster 
as  you  go  higher  up,  because  the  rarer  air 
offers  less  resistance  to  the  motion,  while 
the  propeller  gives  the  same  push  with 
the  same  power,  whatever  the  elevation. 
As  you  get  into  rarer  air  the  propeller 
simply  spins  round  faster. 

A 50-mile-an-hour  machine  flying  two 
miles  high  in  the  air — and  we  have  ma- 
chines that  have  gone  twice  as  high  as 


that — will  fly  much  faster  than  50  miles 
an  hour. 

Then  at  an  elevation  of  two  miles  high 
in  the  air  there  is  a constant  wind  blow- 
ing in  the  general  direction  of  Europe 
having  a velocity  anywhere  from  25  to 
50  miles  an  hour. 

As  the  net  result  of  all  these  things, 
there  can  be  little  doubt  that  any  ordi- 
nary machine  that  is  able  to  support  it- 
self in  the  air  at  an  elevation  of  two  miles 
high  will  attain  a speed  of  at  least  100 
miles  an  hour  in  the  direction  of  Europe, 
and  that  means  going  from  America  to 
Europe  in  a single  day. 

Calculation  shows  that,  taking  all  these 
circumstances  into  consideration,  our 
best  machines  should  be  able  to  cross  the 
Atlantic  in  13  hours.  I hardly  dare  to 
say  it  aloud  for  publication.  It  is  suffi- 
ciently startling  to  know  that  it  is  not 
only  possible,  but  probable,  that  the  pas- 
sage may  be  made  in  a single  day.  But 
if,  as  I imagine,  it  can  be  done  in  13 
hours,  you  may  take  an  early  breakfast 
in  Newfoundland  and  a late  dinner  in 
Ireland  the  same  night. 

Now,  I will  not  take  up  any  more  of 
your  time.  My  idea  has  been  to  point 
out  to  you  how  great  discoveries  and  in- 
ventions have  originated  from  very  little 
things,  and  to  impress  upon  your  minds 
the  importance  of  observing  closely  every 
little  thing  you  come  across  and  of  rea- 
soning upon  it. 

Indeed,  as  Smiles  very  happily  puts  it, 
“The  close  observation  of  little  things  is 
the  secret  of  success  in  business,  in  art, 
in  science,  and  in  every  pursuit  in  life.” 


